Cool...sexxay.

157mm (6.2") of vertical wheel travel (shock metal to metal) and a 5.7% rising rate over the bulk of the stroke.

Awesome! Nice to know I'm getting 6" of actual travel.

So what does the 6% rising rate over the bulk of the stroke mean (please translate in plain English)? Will this info affect how you tune the shocks from now on?

Looking at the leverage ratio dot plot, it seems like the ratio actually remains the same throughout the travel; i.e. no statistically significant change. If so doesn't that mean that the leverage rate is linear?

So what does the 6% rising rate over the bulk of the stroke mean (please translate in plain English)? Will this info affect how you tune the shocks from now on?

Looking at the leverage ratio dot plot, it seems like the ratio actually remains the same throughout the travel; i.e. no statistically significant change. If so doesn't that mean that the leverage rate is linear?

It means that the suspension between sample points has a rate change of (+) 6%. This means that the suspension rate rises to help increase bottoming resistance toward the end of the stroke. Higher initial leverage for better small bump compliancy, Lower ending number to help in bottoming control. As for the plot, it shows a plot of the rate rise throughout the entire stroke. Note how the left side of the plot is higher than the right side (Rising Rate), not linear. Lastly, we've yet to tune dampers for the 6 Packs at the consumer level, so there would be no changes.

who ya got runnin that thing? jordi la forge? guessin the box on the down tube holds the dilythium crystals.

You may laugh, but I actually had to Google that name to find out what you were talking about!

Does that information suggest that one setup will be better for the 6 pack than another,ie an Air or a Coil, or is 5.7 % not the factor, both air and coil can be tuned to suit.

Not necessarily, however I'm a fan of the coil personally.

Yeah, while you're at it, can you explain the whole "regressive travel" thing in regards to running a 2.25" stroke shock on the RFX/6-pack?

I'm not familiar with the "regressive" term in regards to suspension? Running a 7.875 x 2.25" stroke on a DHX I'm sure would produce a number of geometry issues, both in suspension and chassis though. It would change the starting and ending angles of the rockers which would alter the leverage ratio significantly as well as change the BB and HA of the frame.

Regressive=Amount of force required to compress an inch is increasing as it goes through travel, except for each inch, it's a lesser amount of force. A regressive curve will reach a point at which it begins to become digressive. So to compress one inch might take 400lbs, to compress another inch will take 500lbs, to compress another inch will take 450lbs, if the curve continues it will approach linear, and the start to digress, which will be "falling rate". Some bikes can have a regressive spring curve, and they run out of travel before it gets "linear" or "falling rate".

Digressive=Amount of force required to compress an inch is less as travel is increased.

Lastly, the problem with putting a longer stroke shock on many bikes, linkage or otherwise, is that if you could keep increasing the stroke of the shock, maintaining the same eye to eye (or even slightly different) you'd reach a point where the suspension would become a falling-rate, because the eyelet hole of the linkage will eventually start to move away from the eyelet hole of the frame. This means the rate of the suspension is changing past what it was designed with, so, with 6" of travel a certain bike might have a linear or progressive rate, and when you increase travel by increasing the stroke of the shock the suspension starts to get either regressive or digressive, in not as many words it's a good way to screw up your suspension and run into a plethora of other problems.

Last edited by Jayem; 10-11-2005 at 08:38 PM.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

The "regressive" thing came up here: in regards to pushing a 7.5x2.25" fox vanilla RC for use on a RFX or 6-pack. I was curious about it since I got the push factory race system done on my 7.5x2.25 vanilla RC. With 6" rockers, this produces an extra 3/4" of travel, compared to the stock 7.5x2.0" shock. I'm asking about it here, because I was curious why Bulldog and I got different stories about your willingness to service the 7.5x2.25 vanilla. Perhaps this was all a miscommunication.

A bunch of us with RFX's have played with this and found that a few diferrent rocker designs were produced for the RFX, some have tire clearance issues with the 7.5x2.25 shocks and others don't. yeah, we have kind of a shock cult going on.

For the record, my set-up works great. Plenty of tire clearance with michelin DH 2.5's, the shock does not bob, or bottom out on flat landings. It's seen moab, whistler and plenty of north vancouver this year on top of the local seattle rides, so I've put it through the paces. If anything, I think it could benefit from slightly less compression damping. I do much prefer the pushed 2.25" RC to the other shocks I have had on this bike (fox RP3 and romic). Not to mention, I really appreciated the time you and Jimmy spent with me on the phone. Good stuff!

Originally Posted by PUSHIND

I'm not familiar with the "regressive" term in regards to suspension? Running a 7.875 x 2.25" stroke on a DHX I'm sure would produce a number of geometry issues, both in suspension and chassis though.

Damping curves:
Linear = Damping force increases proportionate to velocity
Digressive = Aggressive initial damping values followed by a sharp leveling where damping value remains the same no matter how much the velocity is increased.
Progressive = Damping curve where force increases are disproportionate to velocity.

Oh yeah

FM,

Now it's clear. As for the RFX thing, we had/have some conflicting results/data that prevent us from moving forward with that setup. As for your bike, or others that we've set up in the past, we'll still continue to offer service/support.

Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

So basically, no problems pulling extra travel out of the RFX using a 2.25" stroke shock, but the old vanilla RC may not be the best candidate due to it's design limitations. (i'm guessing lack of oil volume, etc) Makes me think: perhaps this is why fox quit making this weird size to begin with!

I think it's awesome when the people behind the products (like yourself or Dave Turner) hop on the boards here to clear stuff like the up in person- thanks again.

Originally Posted by PUSHIND

Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

Damping curves:
Linear = Damping force increases proportionate to velocity
Digressive = Aggressive initial damping values followed by a sharp leveling where damping value remains the same no matter how much the velocity is increased.
Progressive = Damping curve where force increases are disproportionate to velocity.

This remains true whether Motorsport or bicycle.

Darren

How would you describe each of these then?

One the first one, it goes from ~linear to falling rate.

The second one is linear, the amount of force to compress an additional inch is always the same.

On the third one the amount of force to compress an inch is increasing with travel, but the rate at which it is increasing is actually decreasing. This is key to describing what we are talking about. If you don't believe there are bikes that share this trait, you need to do some more research.

The fourth one is progressive, the amount of force required increases with each additional inch.

What is it?

This is key to describing what we are talking about

Who is "we"

you need to do some more research.

That's what we do everyday here at PUSH. That's why this whole post exists. There is an astronomical amount of time, money and energy being put into this equipment and we take what we do very seriously.

At this point I feel like your comments aren't meant to be constructive, but rather to attack either myself or my company. In your post you don't provide the information to whether your lines are for leverage rates or damping curves, in either case your infromation describing them is incorrect.

I would be curious as to your profession, but it appears that you work in the industry?

Now it's clear. As for the RFX thing, we had/have some conflicting results/data that prevent us from moving forward with that setup. As for your bike, or others that we've set up in the past, we'll still continue to offer service/support.

Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

Do you have any experience with the new Cane Creek Double Barrel shock

No but I did have it's big brother, the Ohlins TTX40 in for an application last year. I have huge respect for Ohlins, but have no experience with the Cane Creek unit. It doesn't seem like there are many out there.

H
On the third one the amount of force to compress an inch is increasing with travel, but the rate at which it is increasing is actually decreasing. This is key to describing what we are talking about. If you don't believe there are bikes that share this trait, you need to do some more research.

.

I think there is an issue here with terminology. Darren probably lumps this under the general term of rising rate since even though it's not linear, it's still rising. Your terminology seems to originate from the regressive tax idea the tax rate decreases as income increases. I suppose you can use this terminology here but is it really used in the industry?

I suppose you can use this terminology here but is it really used in the industry?

The real question is, will it feel the same or different, because if there's a difference in how it works and feels, that's probably enough justification to call it something different.

It also is very important because you can see that after a while, it becomes linear, and then starts as a falling rate, so this is visually showing people that if they keep increasing the travel of their bike (like by putting a longer stroke shock on) it will become a falling rate.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

It means that the suspension between sample points has a rate change of (+) 6%. This means that the suspension rate rises to help increase bottoming resistance toward the end of the stroke.

Lastly, we've yet to tune dampers for the 6 Packs at the consumer level, so there would be no changes.

Darren,

Thank you for your response and clarification. The plot makes more sense to me now.

So if you do a regression statistical analysis on the scatter/dot plot (leverage ratio curve) above then you may show a slight decrease in leverage ratio over the bulk of the stroke. How is the % Rise in Rate calculated? Surely, there must be some kind of statistical model used in the calculation or is it based on random points on the plot?

I also see a wavelike pattern in the scatter plot; is that normal? Does the leverage ratio cycle through the stroke?

Originally Posted by PUSHIND

Higher initial leverage for better small bump compliancy, Lower ending number to help in bottoming control. As for the plot, it shows a plot of the rate rise throughout the entire stroke. Note how the left side of the plot is higher than the right side (Rising Rate), not linear.

In that case, we really don’t need much bottom-out control on the shock, then. Am I interpreting this correctly? If so, then a PUSH'd Vanilla RC or an Avalance will work just as well as the DHX on the Pack. Your thoughts?

Originally Posted by PUSHIND

Lastly, we've yet to tune dampers for the 6 Packs at the consumer level, so there would be no changes.

Bring it on, baby...!!!

Originally Posted by PUSHIND

Who is "we"

That's what we do everyday here at PUSH. That's why this whole post exists. There is an astronomical amount of time, money and energy being put into this equipment and we take what we do very seriously.

At this point I feel like your comments aren't meant to be constructive, but rather to attack either myself or my company. In your post you don't provide the information to whether your lines are for leverage rates or damping curves, in either case your infromation describing them is incorrect.

I would be curious as to your profession, but it appears that you work in the industry?

Darren

It looks like Darren is calling Jayem out. I'll pay to watch this. Right now I give Darren the early lead, because (a) he's making a living at doing this so obviously knows more than a thing or two, and (b) he is not hiding behind a secret indentity...got to give a guy credit for putting his personal brand on the line. Let's get ready to rumble....

It looks like Darren is calling Jayem out. I'll pay to watch this. Right now I give Darren the early lead, because (a) he's making a living at doing this so obviously knows more than a thing or two, and (b) he is not hiding behind a secret indentity...got to give a guy credit for putting his personal brand on the line. Let's get ready to rumble....

I think there is simply a communication and a rapport problem here. They both seem to know a thing or two. It's just that Jayem pushed (excuse the pun) on Darren a little in his thread. I see Jayems point it's just he didn't convey it well to Darren perhaps.

It looks like Darren is calling Jayem out. I'll pay to watch this. Right now I give Darren the early lead, because (a) he's making a living at doing this so obviously knows more than a thing or two, and (b) he is not hiding behind a secret indentity...got to give a guy credit for putting his personal brand on the line. Let's get ready to rumble....

Who's "hiding" behind a "secret identity"?, are you trying to get people to post their home address and number?? Makes no sense. What's your home address and phone number?

Darren hasn't come back and explained if what I showed was in fact what I claimed it to be, he's danced on the issue a bit, but I've posted the progression-charts to show exactly what I was talking about, and I described it in words. What more could one ask? Either it would feel different and it would play a role, or it wouldn't, and we are looking to get some input on this subject. The regressive "rate" will become linear, and eventually become falling rate, which is very much along the lines of what was originally said about using a longer stroke shock on the a particular bike, because you'll loose the progressive travel at the end of the travel. There's a decent amount of bikes out there that have spring curve #3 (diagram), most of them use a progressive shock though, but again, maybe it plays a role and maybe it doesn't, maybe if you put a longer stroke shock on there you could make up for the change in rate at the end of travel with a progressive shock.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

Who's "hiding" behind a "secret identity"?, are you trying to get people to post their home address and number?? Makes no sense. What's your home address and phone number?

Darren hasn't come back and explained if what I showed was in fact what I claimed it to be, he's danced on the issue a bit, but I've posted the progression-charts to show exactly what I was talking about, and I described it in words. What more could one ask? Either it would feel different and it would play a role, or it wouldn't, and we are looking to get some input on this subject. The regressive "rate" will become linear, and eventually become falling rate, which is very much along the lines of what was originally said about using a longer stroke shock on the a particular bike, because you'll loose the progressive travel at the end of the travel. There's a decent amount of bikes out there that have spring curve #3 (diagram), most of them use a progressive shock though, but again, maybe it plays a role and maybe it doesn't, maybe if you put a longer stroke shock on there you could make up for the change in rate at the end of travel with a progressive shock.

I have a question or three.
Where are you getting these rate charts?
What reference are you using that regression is defined?
What bikes have this "spring diag. #3" spring curve and where did you come by this information?

I have a question or three.
Where are you getting these rate charts?
What reference are you using that regression is defined?
What bikes have this "spring diag. #3" spring curve and where did you come by this information?

The rate charts are samples, typical of what is found when you measure the rate of many bikes, in this case, they come from the linkage program that maps out the rates of different bikes.

Reference for digression? Just the fact that the rate of increase is decreasing, and eventually it becomes linear, and eventually falling (if you were to continue the line).

Many bikes have "spring curve #3", Iron Horse MIII hollowpoint, kona stinky, ventana X-5, specialized enduro, RM ETS...These are just a few, a few that I happen to have in my linkage program, and I haven't gone through all the bikes and catagorized them in this respect(so if I sit here for an hour I could tell you a lot more of them). This sample cross-section of bikes shares this trait to varying degrees, on some it's pretty extreme, and on others it's slight. There's quite a few bikes out there with this tendancy, as there are also a lot of falling rate and rising rate bikes, not too many linear ones though on all the bikes that I've mapped out.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

The rate charts are samples, typical of what is found when you measure the rate of many bikes, in this case, they come from the linkage program that maps out the rates of different bikes.

Reference for digression? Just the fact that the rate of increase is decreasing, and eventually it becomes linear, and eventually falling (if you were to continue the line).

Many bikes have "spring curve #3", Iron Horse MIII hollowpoint, kona stinky, ventana X-5, specialized enduro, RM ETS...These are just a few, a few that I happen to have in my linkage program, and I haven't gone through all the bikes and catagorized them in this respect(so if I sit here for an hour I could tell you a lot more of them). This sample cross-section of bikes shares this trait to varying degrees, on some it's pretty extreme, and on others it's slight. There's quite a few bikes out there with this tendancy, as there are also a lot of falling rate and rising rate bikes, not too many linear ones though on all the bikes that I've mapped out.

Darren came here with goodwill to show us what he's been up to and he gets interrogated on what he knows. Darren doesn't have to prove himself, especially since his products have proven themselves many times over.

Who's "hiding" behind a "secret identity"?, are you trying to get people to post their home address and number?? Makes no sense. What's your home address and phone number?

Nothing personal, man...just dicking around when I should have been working. I do hide behind my secret identity, and I probably don't have as many super powers as FM does.

I do appreciate the technical aspects of your points, by the way...in my humble way of looking at it, you are trying to differentiate suspension travel based on the second derivative of the actual travel plot..."yes, it is increasing, but is it increasing at an increasing or decreasing rate..."

The question I personally have about all of this is one of relevance (not trying to slam anyone here, just pose an open question). The analysis of suspension rates, axle travel, instant center location, blah blah blah whatever, might be interesting on paper, but the real test is how they work and feel when we ride. One design might be 20% more efficient in some aspect than some other design, but if that difference is occuring at a time when some other factor is operating at input levels that are orders of magnitude higher, how much does it really matter? Not to beat a dead horse (but I will), maybe the TNT designs have a brake caliper location that theoretically causes some jack, or squat, or who the heck knows what, impacting suspension motion. But if that negative factor is occuring with a value of X, and the suspension cycling due to inputs from the road at levels of 10X, would we ever really be able to feel the difference? That to me is the real question. We've seen lots of great analysis on paper, but not a lot of it from people who actually design and sell the bikes or suspension bits that we like so much. We test their work on our own butt-o-meters, decide what we like and don't like, and then reverse engineer all sorts of b.s. to convince ourselves why this design is better than the last one we rode.

I think that is an important point to remember in all of this. It is extremely important for most of us to prove to ourselves and others that this latest, greatest bike or bit we just bought is not only superior on the trail, but on paper as well because otherwise we would be just throwing our hard earned money away on marketing hype. I, for one, am not among the fortunate few whom have the resources (time and money) to ride many different designs and discern meaningful differences between the best of the best. And even if I had the time and resources, I doubt I have the talent level to push any of these rigs to the point where the differences between them would become evident to me.

This is just one (anonymous, non-super hero) person's opinion. It's about the ride. Talking about it is good, healthy dicking off; arguing about it can also be entertaining. But I will leave it at that. Darren makes his living tuning these systems for racers and consumers alike, and I respect that he lays it on the line every day, even more so when he steps out from behind the secret identity of "PUSH Industries" to talk to us directly. It is smart marketing, but can be risky if you are not straight up, honest, and good at what you do. Others have tried to do what DT, Larry and now Darren have done, and have not been as successful.

Darren came here with goodwill to show us what he's been up to and he gets interrogated on what he knows. Darren doesn't have to prove himself, especially since his products have proven themselves many times over.

LOL! Well Darren obviously cares about all this....and perhaps a lot of us do too (I do). So what is wrong with a little critic? in fact, it's healthy for everyone to argue about this.

I work in the sciences and this is nothing compared to the challenges brought up by peers in my dicipline! Good science is questioning all assumptions, data, and conclusions. Bad science is taking things at face value and accepting it. When Darren studies suspensions, he is doing science.

Darren has a lot of experience but if he knew it all, he wouldn't need to study it like he is doing. People in technology can't work in a vacuum (unless you are a vacuum scientist) and need to be open to criticism.

stuff

My eyewear! How dare you question my choice. Actually they're custom from Oakley and include the PUSH Logo laser fired into the lower part of the lens! Take that

Anyway, much like when you guys get new components and like to show the bling, I get excited with my new toys. That's really the only reason for the post. I've come to know quite a few of you via trail/e-mail/phone, and was just showing what Santa brought early to a community that we at PUSH are feeling a part of.

The purpose behind the leverage ratio tools, much like the on-board system, is to allow us to better understand suspension characteristics and to be able to apply consistant tuning variables to similar appliactions. As you can imagine, the couple of screenshots that I posted are only a peek into what the software is capable of and, when used in conjunction with on-board DAQ as well as all of the tuning and prototyping capabilities we have, some pretty cool things can happen. We know by riding a Six Pac, Nomad, and SuperMoto that the frames react differently to bumps and rider input, but this lets us better understand the differences.

Also, We work in an absolute world at PUSH and always like to quantify rider feedback and computer model/simulation. We also understand that theoretical and actual can be very different. Case in point would be these online leverage ratio programs. They provide a nice baseline to go of off, but in reality the actuals don't match the linkage program theoretacals. This can easily be seen by taking our actual 6 Pack data and comparing it to the theoretical linkage software simulation. The numbers don't match. Our numbers come from a tangible bike that you can throw a leg over. Working with real data is what is useful to us.

So why all of the fuss? Well, because when our customers tell us that they really like something, we want to be able to re-create that product performance for customers with a different application. We want to learn what makes a suspension component perform better than another at the consumer level. 5 Spot owners spoke up and had a lot to say about the new DHX-Air. The RP3 vs. DHX Air debate began. We listened, we tested, and we re-created characteristics that you as riders told us you liked. We can now add that to our database and continue to listen, learn and test. This gear just is another step to making our job easier and more consistent.

It's about the ride. Talking about it is good, healthy dicking off; arguing about it can also be entertaining. But I will leave it at that.

totally agreed, especially after the TNT debacle here. I like nice bike parts and the engineering behind them, don't we all... but it just comes down to the ride for me. Personally I could care less about debating physics, engineering or aesthetics... none of that is going to change the experience of riding a bike.

totally agreed, especially after the TNT debacle here. I like nice bike parts and the engineering behind them, don't we all... but it just comes down to the ride for me. Personally I could care less about debating physics, engineering or aesthetics... none of that is going to change the experience of riding a bike.

How wrong you are! Someone, somewhere had to debate physics, engineering and aestherics to create the ride you are enjoying. You might not care, but it happened. They did it and you enjoy it when you ride....You might not care, but you should!

How wrong you are! Someone, somewhere had to debate physics, engineering and aestherics to create the ride you are enjoying. You might not care, but it happened. They did it and you enjoy it when you ride....You might not care, but you should!

Yeah, but for the most part the guys who do it for real are not the same ones who dick around on these forums debating whether or not an angular moment affects the braking performance when the axle is mounted on the seatsay vs. the chainstay, and/or whether the angle of the rocker negates that moment...and/or...oh crap...my head hurts.

It's all just dicking around to me...like they say--guys that can do, guys that can't teach, and guys that can't teach dick around on the boards talking about it.

Not that there's anything wrong with that

You all should be ashamed of yourselves. Now get out of here and go for a ride.

debating frame/shock design with someone who, like me, has a non-cycling related desk job: total waste of my time.

I used to work for a local custom frame shop. If I had a nickel for every letter we recieved from somebody with an interesting, but ultimately worthless design opinion/suggestion, I would still be working in the bike industry.

The rate charts are samples, typical of what is found when you measure the rate of many bikes, in this case, they come from the linkage program that maps out the rates of different bikes.

.

A linkage program that is flawed. I have pointed that out to you twice, Jayem, yet you insist you are correct. You are arriving at conclusions based on this program, and are shutting out real world data. That is NOT scientific method. For example, I have posted this picture of an '01 dare that I owned several times here at mtbr, seen here:

Twice, Jayem posted that the seastay brace would collide with the saddle at the height that the saddle was set. Twice, I replied that no, it would not, I have had the spring off the shock and completely compressed the suspension, and there is no collision. Jayem still insists that he is right, based on the linkage program he is using. What would you believe, a real world test that is pure black and white, or assumptions based on a linkage program downloaded off the internet?
To quote Darren; " theoretical and actual can be very different. Case in point would be these online leverage ratio programs. They provide a nice baseline to go of off, but in reality the actuals don't match the linkage program theoretacals. This can easily be seen by taking our actual 6 Pack data and comparing it to the theoretical linkage software simulation. The numbers don't match. Our numbers come from a tangible bike that you can throw a leg over. Working with real data is what is useful to us."

So, who are you going to believe, a professional who who works in the field everyday, and uses multiple means of gathering and processing data and puts that knowledge to work in trial and error tests, or a stubborn amateur making conclusions sometimes from just a photograph?

, Jayem posted that the seastay brace would collide with the saddle at the height that the saddle was set. Twice, I replied that no, it would not, I have had the spring off the shock and completely compressed the suspension, and there is no collision.

Well, I didn't say that had to happen, some ellsworth bikes are notorious for not getting the claimed travel. What I said was, that if it got the claimed travel, it would run into the seat. If the brace doesn't run into the seat, it doesn't get the claimed travel. It's that simple. The program doesn't lie, but tony ellsworth does. There are a good deal of past-dare owners that know about this problem, and they've reported it here.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

Well, I didn't say that had to happen, some ellsworth bikes are notorious for not getting the claimed travel. What I said was, that if it got the claimed travel, it would run into the seat. If the brace doesn't run into the seat, it doesn't get the claimed travel. It's that simple. The program doesn't lie, but tony ellsworth does. There are a good deal of past-dare owners that know about this problem, and they've reported it here.

No, you didn't say that at all, what you said the second time around, and I quote you, "No, that's a bike where the seatstay yoke will slam into the seat." at this thread; the Dare LIVES I captured your quote here in case you go back to edit it.
You didn't say what you claimed you said the first time around either. I was the one that told you the '01 dare only got 7 inches of travel, and I told you that the first time you made your statement, and you still posted the same erroneous observation the second time. Poor attempt to cover your ass and save some face Jayem.
And why, doesn't the program lie? Is it perfect? Wasn't it a program created by a human? Do humans not err? How can you vouch for the perfectness of the program, when real world testing has shown it to be in err? Or why don't you just give up on this topic, and not lose more credibility?
__________________

In a slight defense of Jayem, I see what his point is with the "regressive" idea and he pointed out the scenario where someone uses a longer stroke shock to get more travel. An example of this would be in a monopivot bike like a Heckler. If you have a long enough stroke, you will reach the point where the leverage ratio starts rolling over and eventually becomes a minimum--and could even pass and reverse in rate.

Sure, maybe this is not happening in most "real" world situations but it can certainly happen in theory. An open minded engineer, even working only on existing stuff, should understand this and consider it when studying these systems. Innovation comes from this looking at the boundaries of these situations and exploring what happens there-- the proverbial, stepping outside the box.

I laught at you people who tell the engineering types to just "go for a ride". Some of us actually like to stress over the small details and try to determine how a bike will ride before actually hopping on the saddle. And you tell me that there's something wrong with that?! Bottom line - physics doesn't lie - conclusions made from data actually do mean something. Which is exactly what Darren appears to be doing with the data acquisition system.

This is definitely a confusing topic. I am also confused by the terminology being used.

Is JM's 4th graph really describing a progressive suspension? The rate does not appear to "increase" progressively, but it does increase in a linear fashion. Linearly progressive? Progressively linear? How do you describe this?

This is simply an argument over terminology, there is no reason to yell at each other!

Is JM's 4th graph really describing a progressive suspension? The rate does not appear to "increase" progressively, but it does increase in a linear fashion. Linearly progressive? Progressively linear? How do you describe this?

He didn't label it but it's correct. These curves are the derivatives of the shock force curves versus rear wheel travel. A constant rate like a spring will have a flat look. IF you integrate the one on the right, you get a quadratic which is the represents the force of the shock, versus the position of the rear wheel--like an air shock.

"Linearly Progessive" is prolly a good way to describe the last curve and Jayem used "regressive" on the 3rd curve. I suppose you could also call the 3rd curve "diminshingly progressive"

The second one is linear, the amount of force to compress an additional inch is always the same.

On the third one the amount of force to compress an inch is increasing with travel, but the rate at which it is increasing is actually decreasing. This is key to describing what we are talking about. If you don't believe there are bikes that share this trait, you need to do some more research.

The fourth one is progressive, the amount of force required increases with each additional inch.

Run this through the linkage program: '02 RFX, with an 8.5 by 2.5 shock, 2.8 to 1 leverage ratio. Seven inches of travel. The rockers mimic the stock rockers; no change from original geometry whatsoever. Tell me that the seatstay arch will collide with the seatube or that the tire collides with the seatube. Convince me of it with the flawless program. Go ahead. I know different.

Run this through the linkage program: '02 RFX, with an 8.5 by 2.5 shock, 2.8 to 1 leverage ratio. Seven inches of travel. The rockers mimic the stock rockers; no change from original geometry whatsoever. Tell me that the seatstay arch will collide with the seatube or that the tire collides with the seatube. Convince me of it with the flawless program. Go ahead. I know different.

What is your point? No one ever said the program was flawless. As long as you input the correct points and use the correct scale, it should reasonable accurate. The methods of calculation are correct, the only way for there to be noticeable error is due to human mistake.

I think the problem is some people use it as a definitive reference for the argument against tnt and a miriad of other things like what was discussed in this thread. If it is flawed, then the argument should be something like;

'I believe the increase in shock stroke may cause the leverage ratio to switch from a rising rate, to a falling rate. My theoretical program is the basis for this.'

But that is not what happens. Instead, you get people arguing that this is absolute fact and they cannot be convinced otherwise.

What is your point? No one ever said the program was flawless. As long as you input the correct points and use the correct scale, it should reasonable accurate. The methods of calculation are correct, the only way for there to be noticeable error is due to human mistake.

My point is this; Jayem has made conclusions based soley on this program regardless of the reality of other, measurable empirical data, and his insistence and stubborness brings out the same characteristics in me, pitted againts him. My remarks in this thread are aimed at him, and only him.

I think the problem is some people use it as a definitive reference for the argument against tnt and a miriad of other things like what was discussed in this thread. If it is flawed, then the argument should be something like;

'I believe the increase in shock stroke may cause the leverage ratio to switch from a rising rate, to a falling rate. My theoretical program is the basis for this.'

But that is not what happens. Instead, you get people arguing that this is absolute fact and they cannot be convinced otherwise.

Right, a computer program is only as smart as the person operating it.

I'm not implying that JM is stupid, what I mean is that one of you is probably assuming something that is not true. There is obviously a difference between what JM modeled and your bike.

Jayem, are you telling us by your comment above that your analysis is based on measurements taken off of photos of bikes? If so, are you sure that is accurate enough to draw meaningful conclusions?

When you described your curves and terminology, you were using the term "force" as in "the amount of force required to compress the suspension one inch..." You were trying to describe different linkage designs, were you not? If so, then "force" has nothing to do with it, you are actually charactering the amount of excursion the shock will experience for a given amount of rear wheel travel at various points in the axle path. Or something like that. Bust my chops if I got this one wrong. But if I didn't, some friendly advice from an old guy who's been there, done that...mistakes like that can be fatal in the real world (which these boards aren't). There will always be a sharpshooter sitting out there waiting for you to slip up...don't give them anything to work with.

And while I am at it...let's hear more about this suspension program that you rely on. I've already asked about your data inputs--you might be able to make some points with the boys if you can show them that you are not dealing with "garbage in/garbage out." But what about the actual calculations themselves. Is this application commercially available, and if so what is it? Is it something you programmed yourself? For hobby, or for academic or professional research? Or is it a proprietary tool developed by one of the companies in the industry?

Everything Jayem knows about physics and mechanical engineering is from reading mtbr and nowhere else. He uses some formal terms but he doesn't know what they truly mean. Ask him to do a few calculations and what formulas are applicable and that's where his knowledge breaks down.

Jayem, are you telling us by your comment above that your analysis is based on measurements taken off of photos of bikes? If so, are you sure that is accurate enough to draw meaningful conclusions?

When you described your curves and terminology, you were using the term "force" as in "the amount of force required to compress the suspension one inch..."

Force has everything to do with the rate of the suspension. Force is what compresses your spring. A progressive bike will require more force for each additional inch. A linear bike will require the same force for every inch, a falling rate will require less force for each susequent inch. Force has everything to do with the rate. This has nothing to do with the wheelpath or axle path, but everything to do with the rate of the bike.

The linkage program maps out the bike based on where the pivots are at, and it "draws" over a side-photo of the bike, there is some possibility of human error, but when I plug in a bike into the program I usually do it a few times to see if the results I get are reliable. It's not an end-all, but it does show you some interesting things.

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

The linkage program maps out the bike based on where the pivots are at, and it "draws" over a side-photo of the bike, there is some possibility of human error, but when I plug in a bike into the program I usually do it a few times to see if the results I get are reliable. It's not an end-all, but it does show you some interesting things.

He's using the Zonoskar linkage program, which has been floating around on the web for years. It's an atiquated program that is nice for someone interested in seeing some basic points of suspension motion, but it does not compare to anything current or more powerful that engineers and designers use to design and analyze their bikes. Not even close. That's why it's a "small file". It's basically MS Paint with some additional applications added to it. Jayem is representing this program as something more than it is (while not specifically naming it).

Accuracy is telling the truth . . . Precision is telling the same story over and over again.

Jayem's program may be precise but I sure do question it's accuracy.

Precision
the degree of refinement in the performance of an operation, or the degree of perfection in the instruments and methods used to obtain a result. An indication of the uniformity or reproducibility of a result. Precision relates to the quality of an operation by which a result is obtained, and is distinguished from accuracy, which relates to the quality of the result. In Figure 1, the marksman has achieved a uniformity, although it is inaccurate. This uniformity may have been achieved by using a sighting scope, or some sort of stabilizing device. With the knowledge gained by observation of the results, the marksman can apply a systematic adjustment (aim lower and to the left of his intended target, or have his equipment adjusted) to achieve more accurate results in addition to the precision that his methodology and equipment have already attained.

Accuracy
the degree of conformity with a standard (the "truth"). Accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of the operation by which the result is obtained. In Figure 2, the marksman has approached the "truth", although without great precision. It may be that the marksman will need to change the equipment or methodology used to obtain the result if a greater degree of precision is required, as he has reached the limitations associated with his equipment and methodology.

Accuracy is telling the truth . . . Precision is telling the same story over and over again.

Jayem's program may be precise but I sure do question it's accuracy.

Precision
the degree of refinement in the performance of an operation, or the degree of perfection in the instruments and methods used to obtain a result. An indication of the uniformity or reproducibility of a result. Precision relates to the quality of an operation by which a result is obtained, and is distinguished from accuracy, which relates to the quality of the result. In Figure 1, the marksman has achieved a uniformity, although it is inaccurate. This uniformity may have been achieved by using a sighting scope, or some sort of stabilizing device. With the knowledge gained by observation of the results, the marksman can apply a systematic adjustment (aim lower and to the left of his intended target, or have his equipment adjusted) to achieve more accurate results in addition to the precision that his methodology and equipment have already attained.

Accuracy
the degree of conformity with a standard (the "truth"). Accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of the operation by which the result is obtained. In Figure 2, the marksman has approached the "truth", although without great precision. It may be that the marksman will need to change the equipment or methodology used to obtain the result if a greater degree of precision is required, as he has reached the limitations associated with his equipment and methodology.

I was a friend of an old guy living near me (now deceased) who taught me everything I know about guns and marksmanship. He was an expert shot and hunter. One of his sons was a world class competitor in the running boar event.

He once killed an elk by firing at it twice. The second shot was for insurance when the elk bolted and ran. When they dressed out the elk they found only one bullet hole. But two bullets were found inside. After closer inspection the bullet hole could be seen to be slightly ovalized. It was really two bullet holes. He had that hide with the hole hanging in his cabin.

He's using the Zonoskar linkage program, which has been floating around on the web for years. It's an atiquated program that is nice for someone interested in seeing some basic points of suspension motion, but it does not compare to anything current or more powerful that engineers and designers use to design and analyze their bikes. Not even close. That's why it's a "small file". It's basically MS Paint with some additional applications added to it. Jayem is representing this program as something more than it is (while not specifically naming it).

This program is somewhat of a novelty and interesting to play with, but nowhere near scientifically accurate.

one example is that a lot of people have used this program to rip on Specialized because of their claim of FSR suspension having a 'near vertical wheel path'. The program includes a graph in its normal output that "magnifies" the axle path to show it as being an ovalized path.

The following graph is from the output of a Turner 6-Pack, however I have "fixed" it. The scale in red on the x-axis is one matching the scale of the y-axis. Looks quite a bit different, doesn't it?

This program is somewhat of a novelty and interesting to play with, but nowhere near scientifically accurate.

one example is that a lot of people have used this program to rip on Specialized because of their claim of FSR suspension having a 'near vertical wheel path'. The program includes a graph in its normal output that "magnifies" the axle path to show it as being an ovalized path.

The following graph is from the output of a Turner 6-Pack, however I have "fixed" it. The scale in red on the x-axis is one matching the scale of the y-axis. Looks quite a bit different, doesn't it?

Well duh. We all learn in gradeschool that graphs are sometimes misleading because of different scales on the x and y axis. The reason the program only shows the extents of the axle-path, is so that there is great detail when comparing two axle-paths. The problem here lies in the person examining the graph, NOT the program.

People rip on Specialized because their designs DO NOT have a vertical axle-path like they claim. FSR bikes are designed to have low chaingrowth, and this would not be possible with a vertical axle-path. "Vertical Axle-Path" is simply a marketing term in this instance.

It's an atiquated program that is nice for someone interested in seeing some basic points of suspension motion, but it does not compare to anything current or more powerful that engineers and designers use to design and analyze their bikes.

And this is why I'm not using it to determine suspension forces, torque forces, anti-squat, blah blah blah. Just simple stuff like the rate...

"It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

And while I am at it...let's hear more about this suspension program that you rely on. I've already asked about your data inputs--you might be able to make some points with the boys if you can show them that you are not dealing with "garbage in/garbage out." But what about the actual calculations themselves. Is this application commercially available, and if so what is it? Is it something you programmed yourself? For hobby, or for academic or professional research? Or is it a proprietary tool developed by one of the companies in the industry?

C'mon Jayem, you make all your engineering conclusions over the internet based on less information than I allready have provided you. I thought you were good....

So, if you had a good side photo, you would come to guesstimate where my pivot locations are, and then run the linkage program from there? You would start off your work with potentially faulty data? No wonder you come to all the screwy conclusions that you do.

Well duh. We all learn in gradeschool that graphs are sometimes misleading because of different scales on the x and y axis. The reason the program only shows the extents of the axle-path, is so that there is great detail when comparing two axle-paths. The problem here lies in the person examining the graph, NOT the program.

.

Bingo!........................

I am so amazed how this discussion, which started out "qualitative" has evolved into a nitpicking debate about details that are more quantitative.

Let me see if I understand this:

Jayem put some "qualitative" graphs of different suspension rates, wanting to answer some terminology questions.

Now we are arguing whether the program is calculating the the wheel path correctly. And whether Jayem is a Hack.

Seems like there is some kettle pot black going on here in the technical finger pointing too.

I rode my Burner to work today and put myself in a trance trying to feel my suspension as a result of this thread. Whether that is a good thing or bad thing, I don't know. All I know is it was a beautiful morning to be out riding and I wish I could go spend a month with Darren learning all this stuff about bike suspensions.

Btw, Rene, If all you want to answer is whether the program will say if the rear will hit the seatpost, one can use the photo and a ruler compass and protractor and figure that out. I know that kinda is your point but I bet you can also get accurate enough pivot point using the photo and some scale techniques to model that well in the software.

Well duh. We all learn in gradeschool that graphs are sometimes misleading because of different scales on the x and y axis. The reason the program only shows the extents of the axle-path, is so that there is great detail when comparing two axle-paths. The problem here lies in the person examining the graph, NOT the program.

People rip on Specialized because their designs DO NOT have a vertical axle-path like they claim. FSR bikes are designed to have low chaingrowth, and this would not be possible with a vertical axle-path. "Vertical Axle-Path" is simply a marketing term in this instance.

Show me where they claim absolute vertical axle path.

And if we "all' learn this, then why do so many point to these graphs as proof of the ovalized axle path?

Originally Posted by WheelieMan

The reason the program only shows the extents of the axle-path, is so that there is great detail when comparing two axle-paths.

BS. You look at the graph below and tell me what is more telling. Comparing the "magnified" axle paths (blue versus purple), or the true axle path graphs (red versus green). The "magnified" paths are pure crap. You can't tell the difference btwn the 2 bikes using real data?
(Note: the scale on the graph is linear in x and y axis. The "magnified" paths are simply cut and overlayed to refute "...shows the extents of the axle-path, so that there is great detail when comparing two axle-paths")

I am so amazed how this discussion, which started out "qualitative" has evolved into a nitpicking debate about details that are more quantitative.

Let me see if I understand this:

Jayem put some "qualitative" graphs of different suspension rates, wanting to answer some terminology questions.

Now we are arguing whether the program is calculating the the wheel path correctly. And whether Jayem is a Hack.

I am not calling anyone a hack. (boy that was pretty funny, kettle, pot, hack... do you have your own rimshot in the background? )

My problem is with this program. JM is using 'qualitative' graphs that he has pulled from this program. And the context which he posted this was that a longer shock stroke would result in this 'regressive' behavior. I simply wanted to know where this came from. However, when I found that it was the linkage program, I lost quite a bit of faith in his posts, not because I think Jm is full of it, but rather because I do not trust that program for anything other than the novelty that it is.

Jm tried to answer the question regarding the longer stroke using these qualitative graphs that frankly, I question. The original post was quantitative in nature, and if Darren chooses to use his equipment to test the actual change in leverage ratio, I will have faith in this.

And if we "all' learn this, then why do so many point to these graphs as proof of the ovalized axle path?

BS. You look at the graph below and tell me what is more telling. Comparing the "magnified" axle paths (blue versus purple), or the true axle path graphs (red versus green). The "magnified" paths are pure crap. You can't tell the difference btwn the 2 bikes using real data?
(Note: the scale on the graph is linear in x and y axis. The "magnified" paths are simply cut and overlayed to refute "...shows the extents of the axle-path, so that there is great detail when comparing two axle-paths")

I have to disagree with you. The magnified axle-paths are able to show more than the "true" axle paths. Just by looking at the magnified graphs I can accurately determine the total rearward travel as well as total forward travel. You cannot see this when the x and y scales are the same. You're right, it might be a nice idea for the program to allow you to compare axle-paths visually as well, using your "true" method. But both methods are equally valid and have positives and negatives. Claiming that one graph is "pure crap" because it doesn't suit you is just stupid.

I don't understand your plot. Why do the actual curves intersect at the bottom and the magnified ones don't? Is this what you are trying to show us? Something is wrong here.

At travel equals zero, the actual graphs depict this intersection, but the magnified paths do not.

Looking at the magnified paths, you would think that the heckler had a larger variation in wheel path in the horizontal axis compared to the balfa. In fact, the heckler has a variation of ~8.75mm versus the ~16mm of the balfa.

Wheelie said the reason the linkage program distorts the graphs is for easy differentiation between bikes. I maintain it only confuses matters.

That is exactly what I am showing. At travel equals zero, the actual graphs depict this intersection, but the magnified paths do not.

Looking at the magnified paths, you would think that the heckler had a larger variation in wheel path in the horizontal axis compared to the balfa. In fact, the heckler has a variation of ~8.75mm versus the ~16mm of the balfa.

Wheelie said the reason the linkage program distorts the graphs is for easy differentiation between bikes. I maintain it only confuses matters.

Hmm, I didn't notice that. I am not familiar with this program you are using, but the graphs should definitely all start at the same point. I still feel that the magnification method is superior as long as the graphs "start" at the same position. The linkage program that I use does this.

That is exactly what I am showing. At travel equals zero, the actual graphs depict this intersection, but the magnified paths do not.

Looking at the magnified paths, you would think that the heckler had a larger variation in wheel path in the horizontal axis compared to the balfa. In fact, the heckler has a variation of ~8.75mm versus the ~16mm of the balfa.

Wheelie said the reason the linkage program distorts the graphs is for easy differentiation between bikes. I maintain it only confuses matters.

If the graph is properly magnified by reducing the x axis, they should still intersect. Now they look like 4 completely different graphs. I don't have the program on this puter so I can't see for myself but something is not right for sure.

However, normally, I would say having a distorted graph is useful, especially if you want to read numbers for example at the peak points, differences at certain locations etc. Graphs are only useful if you have a way to read them. Hell, I do the opposite of magnifying the axis until that looks purely vertical if one wants it to be vertical. That is something a marketing person would do.

BTW, I tried to show the example of a regressive rate by visually using a Heckler pic and some photoshopping with a long stroke shock. Guess what. It doesn't matter because the rear wheel will hit the seatpost before you reach this zone. This is something that path analysis won't show.

If the graph is properly magnified by reducing the x axis, they should still intersect. Now they look like 4 completely different graphs. I don't have the program on this puter so I can't see for myself but something is not right for sure.

However, normally, I would say having a distorted graph is useful, especially if you want to read numbers for example at the peak points, differences at certain locations etc. Graphs are only useful if you have a way to read them. Hell, I do the opposite of magnifying the axis until that looks purely vertical if one wants it to be vertical. That is something a marketing person would do.

BTW, I tried to show the example of a regressive rate by visually using a Heckler pic and some photoshopping with a long stroke shock. Guess what. It doesn't matter because the rear wheel will hit the seatpost before you reach this zone. This is something that path analysis won't show.

OK, I have confused the matter with the graph posted above. The magnified paths are only there to show visually, side by side, how they compare. The scale is different on the linkage program for the two graphs. I will post the magnified and actual path graphs separately, later.

My only point was this;

Looking at the magnified paths, you would think that the heckler had a larger variation in wheel path in the horizontal axis compared to the balfa. In fact, the heckler has a variation of ~8.75mm versus the ~16mm of the balfa.

Originally Posted by lidarman

However, normally, I would say having a distorted graph is useful, especially if you want to read numbers for example at the peak points, differences at certain locations etc.

This is true. However, linkage should use the same scale on the x-axis for all of the graphs so that you could visually inspect and compare graphs, bike to bike. Either that or actually state what the absolute variations in wheel path in the horiaontal plane is, just as I have done above. It would be much more useful than their goofy graphs.